UPDATE 12pm: The FTSE 100 index has climbed almost 1.6% in morning trading after strong late gains overnight on Wall Street.
The UK index of 100 leading shares was up 81.2 points, or 1.58% to 5220.66 points by lunchtime, after a 0.2% fall on Tuesday.
Investors were buoyed by a revival of optimism in the US over corporate earnings, following strong numbers from Johnson & Johnson and tech-giant Apple. Even Goldman Sachs, which reported softer numbers than expected, climbed 2.21%.
Prudential shares gave a strong showing in early trading, up 14p, or 2.77%, to 520p. Miner Kazakhmys was also among the risers, with its share price up 38p, or 3.68%, to £10.72p.
UK household-products maker Reckitt Benckiser shares rose on news it has agreed to buy Durex maker SSL International. Its is 114p higher, or 3.57%, to £33.04p.
The US suffered another volatile day, with the Dow Jones index reversing heavy falls in early trading to end up 75.53 points, or 0.7%, to 10,229.96. It was 140 points lower at one stage.
But concerns about US economic growth following the release of housing data hit the construction and industrial sectors.
Japan's Nikkei 225 average inched down to close down 21.63 points, or 0.23%, or 9,278.83 points on Wednesday, weighed down by worries about a stronger yen and doubts over the US economic recovery.
The market awaits events later this week, including the results of European bank stress tests.
While charts suggest recent falls in the Nikkei may be coming to an end, a number of lacklustre US indicators are keeping investors wary, with few willing to actively buy before Japanese results pick up steam next week.
‘Most significant’ upgrade since launch
Changes happening over coming months
Had accepted British Steel business
Aimed at HNW clients and family groups
Set for 1 April 2019